Adjustment Layers

Adjustment layers allow you to change the appearance of an image or layer—brightness, hue, contrast, etc.,—without making the change a permanent one. Adjustment layers add nothing to your file size, but add a great deal of flexibility. For example, if you were to use the Levels command (Command-L [PC: Control-L]), make a major change to the image, and then save it, your options, should you change your mind, would be limited. Use a Levels adjustment layer instead as it allows for greater flexibility—even after saving.

Click-and-hold on the Create New Adjustment Layer pop-up menu (it's the half-white/half-black circle) at the bottom of the Layers palette and choose the kind of adjustment layer you'd like to use. You can also choose one from the Layer menu, under New Adjustment Layer.

How can I make an adjustment layer only affect one layer? I have added an adjustment layer, but it is affecting all the layers below it. How can I make the adjustment layer affect only one layer?

A3:

Position the adjustment layer in the Layers palette immediately above the layer you want it to affect. With the adjustment layer active, choose Layer>Create Clipping Mask, or press Command-Option-G (PC: Control-Alt-G). Now the adjustment layer will only influence the layer with which it is “clipped.” Note: As soon as you choose Layer>Release Clipping Mask, the adjustment layer will affect all layers below again.